Parent application Ser. No. 08/250,885, filed on May 31, 1994 and its parent application Ser. No. 08/080,727 disclose and claim a genus of adenovirus(Ad)-derived cell expression vectors having excellent potential as live recombinant vaccines and as transducing vectors for gene therapy. In the human Ad genome, early region 1 (E1), E3, and a site upstream of E4 have been utilized as sites for introducing foreign DNA sequences to generate adenovirus recombinants. In the absence of compensating deletions in E1 or E3, a maximum of about 2 kb can be inserted into the Ad genome to generate viable virus progeny. The E1 region is not required for viral replication in complementing 293 cells and tip to 3.2 kb can be deleted in this region to generate conditional helper independent vectors with a capacity of 5.0–5.2 kb. In the E3 region, which is not required for viral replication in cultured cells, deletions of various sizes have been utilized to generate nonconditional helper independent vectors with a capacity of up to 4.5–4.7 kb.
The maximum capacity for inserts of foreign DNA in currently available helper independent Ad vectors such as those described in the parent applications is approximately 8 kb. This limited capacity arises from the use of Ad vectors which have deletions of E1 and E3 sequences and from the fact that most other regions of the viral genome must be retained in order that the viral vector may be propagated without the need for a helper virus.
Besides this limited capacity for insert DNA, previous vectors retain most of the viral genome, making it possible for expression of viral genes in transduced cells or in inoculated animals, including humans, which can result in toxic or other untoward effects. In addition, previous viral vectors can recombine with Ad sequences present in cells used for propagation of the vectors or with Ad sequences that may be present in inoculated animals. Therefore, it is an objective of this invention to provide Ad cloning vectors from which all or most viral genes have been removed and which have increased safety and capacity for larger insertions compared to currently available vectors.